Ferns are great additions to both outdoor and indoor gardens. Sadly, though, if not taken good care of (which is to be expected if you’re still new at handling the plant), they tend to develop several challenges that cause their leaves to turn brown and sometimes cause yellowing on the rest of the plant.
As such, after receiving hundreds of questions akin to, “why is my fern turning brown” I’ve decided to take a deep dive into the subject and help you craft a course of action.
Why is My Fern Turning Brown?
Allow me to start with a disclaimer.
Note that it shouldn’t be alarming anytime you spot new fronds on your ferns that are yellow or light green. Unlike mature leaves, newer ones are usually lighter in color, but they will darken with time.
The oldest leaves at the base of your fern will also usually turn yellow, then brown, and eventually drop off. This is also normal and isn’t cause for alarm.
However, if you notice random leaves on your ferns changing their shade, it’s a sign that something is wrong with the plant, and it’s up to you to evaluate the probable cause. Here are 5 different reasons it could be happening.
1. Acclimation
Sometimes, you have no choice but to move your ferns to a new location; for example, when you move into a new home, decide to change its position in your current home, or even when you bring a new fern home from a nursery.
Better yet, most people prefer to move their ferns outside over summer and bring them back once fall rolls in.
Whichever the case, if you recently moved the fern in question, then probably the change in conditions is causing your plant stress.
The sad part is, even if you try acclimating ferns as slowly as you can, chances are they’ll still develop brown foliage. This doesn’t mean you shouldn’t try and minimize the effects though.
As such, during transitions, ensure you keep the fern’s root ball moist and never let it dry out completely. If you’re planning to take out your fern outside over summer, start off slowly, only placing it outside for a few hours in the early days and progressing as the plant gets acclimatized to the outside environment.
2. Transplant Shock
If you recently tried moving your fern plant to a new pot or propagating it through division, its leaves may be turning brown because the plant is still undergoing transplant shock.
The main reason behind this is chances are you accidentally harmed or damaged the root system during the moving or propagating procedures.
I’ve actually heard of severe cases where transplant shock killed entire fern plants.
With that in mind, to abate transplant shock on your ferns, divide or repot them in late fall or early spring, and avoid doing it in mid-summer since this is usually the period the plant is growing at its highest rate.
Furthermore, avoid shaking out the soil on the plant’s root ball and avoid disturbing the root ball altogether. Try your best not to tamper with the small roots in any sense of the word.
If you already transplanted your fern and it’s undergoing transplant shock, all you can do is give it the time it needs to heal itself. Trim up to one-third of the fern’s foliage and keep the roots moist at all times. Both of these tricks will allow your fern to focus all its efforts on re-growing its roots.
3. Over-fertilization
Easily one of the most versatile houseplants available, ferns do not need a lot of fertilization. Usually, I provide mine with a dilute solution after two to three months.
With that in mind, if you notice fertilizer salt accumulating in the fern’s container’s soil or you’re frequently fertilizing, this could be responsible for why your fern is turning brown.
Over-fertilizing your ferns causes several problems, including but not limited to damaging the roots and causing direct toxicity effects.
To fix fertilizing issues, only fertilize your ferns several times each year using water-soluble fertilizers ad following any instructions given on the fertilizer’s packaging to the latter.
Potted plants like ferns usually need less fertilizer than outdoor ones, so if you’re using a generic fertilizer for all plants in your home, dilute it to half its suggested strength.
Also, only apply the fertilizers directly to the plant’s soil and refrain from getting any on the leaves.
4. Sun
Ferns are adapted to sunlit, but shady conditions and direct sunlight will usually scorch their leaves and turn the whole side of the plant brown. In your home, a northern window is an ideal location to place your fern, as this is where it’ll receive indirect and filtered sunlight.
Note, though, that the angle of sunlight tends to change over time, so ensure you adjust the location of the fern accordingly.
5. Under-watering
For a myriad of houseplants, too much watering is usually the number one cause of issues. With ferns, however, the opposite is true. One of the main reasons ferns start to brown is under-watering, because they like their root balls moist all the time. Do not let them get soggy, though, as that can cause root rot.
If you’ve been watering your fern on a schedule, stop doing that. Instead, start monitoring the fern’s conditions as well as the soil’s dampness to determine when the plant needs watering.
Also, bear in mind that lots of factors, like the choice of soil, the plant’s size, size of the pot, the time of year, and the type of the pot, will impact how often your fern needs water.
Over the winter months, houseplants (including ferns) naturally become dormant and slow their growth, so you can choose to reduce your watering sessions then. Still, though, ensure the root ball remains consistently damp.
Final Thoughts
I’ll agree, ferns are a little bit fussy plants to take care of as a new plant parent, but with these 5 tips, you should have all bases covered to ensure lush, beautiful plants that are an aesthetic addition to your gardens.
If you ever come across another plant parent also wondering, “why is my fern turning brown,” do not hesitate to point them to this list as it can help them identify, troubleshoot, and remedy the possible causes of the browning ferns.